Coupling or transition fitting for the connection of metal or plastic pipes

ABSTRACT

A pipe coupling having a radially deformable housing, wherein a pipe is freely insertable into the housing bore and a nut causes engagement of the grip ring with the pipe. The housing bore including a plurality of outwardly extending projections. The grip ring including a plurality of apertures adapted to receive the housing projections and a plurality of inwardly extending burst hole projections. Tightening of the nut causes the grip ring to be forced both radially and longitudinally, whereby the gripping member substantially restricts longitudinal and rotational movement of the pipe.

[0001] The present invention relates to a coupling or transition fittingfor the connection of pipes of the type having a gripping member. Inparticular it relates to an improvement in the gripping member to enablethe coupling or transition fitting to be used on metal as well asplastic pipes.

BACKGROUND OF THE INVENTION

[0002] Couplings and transition fittings of the type having a grippingmember are well known, see for example Applicants U.S. Pat. No.5,593,186. In general these couplings include a nut, body, grippingmember having a plurality of inwardly directed barbed projections, aswell as a sub-assembly of a compression sleeve and resilient gasket ringthat is typically permanently attached to the inner end of thecompression sleeve. The nut and the gripping member include abuttingtapered surfaces. A pipe end is freely insertable through thesub-assembly and into a socket in the body of the coupling. As the nutis tightened it exerts both a radial and longitudinal force on the gripring that in turn longitudinally exerts a force on the sleeve and gasketring. The gasket ring encounters an abutment in a socket in the body,and further tightening of the nut then further radially compresses thegripping member so that its inwardly directed barbed projections engagethe outer surface of a pipe to which the coupling is attached. There mayalso be provided abutment surfaces within the body of the coupling andthe nut that abut inner and outer surfaces of a flange outstanding fromthe outer end of the compression sleeve.

[0003] One skilled in the art will appreciate that as the nut istightened, the tapered surface of the nut acts upon the tapered surfaceof the gripping member causing it to be both compressed and urged intothe body. As the gripping member engages the pipe it is also drawn intothe assembly.

[0004] Whilst this works well on plastic pipes, it does not work well onmetal pipes because the gripping ring, itself made of plastic material,does not possess sufficient strength or hardness to engage a metal pipe.Annular plastic barbs simply can not engage metal pipes with sufficientresilience and even under a small longitudinal force on the pipe, thepipe generally disengages from the coupling.

[0005] To overcome this problem, it has been known to modify thegripping member to include protruding metal strips or teeth (generallystainless steel) extending longitudinally along the pipe. However, thesemodified gripping members are not suitable for plastic pipes since theplastic is easily damaged and cut by the protruding strips. Further, thesofter the material, the greater the surface contact required betweenthe gripping members projections and the pipe so that in soft pipes theso modified gripping members are generally unsuitable.

[0006] The main object of this invention is therefore to overcome theabovementioned problems or at least provide the public with a usefulalternative by providing improvements whereby the body, nut and grippingmember (compression ring) form a preliminary assembly through which canbe inserted either a metal or a plastic pipe, which is secured bytightening the nut, or removed by unscrewing the nut.

SUMMARY OF THE INVENTION

[0007] Therefore in one form of the invention though this need not bethe only or indeed the broadest form there is proposed a pipe couplingor transition fitting of the type having a deformable gripping memberassembly including a housing and a plurality of metal projectionsextending inwardly therefrom.

[0008] Preferably said housing is annular with said projectionsextending circumferentially inwardly from said housing.

[0009] Preferably said metal projections extend from a metal band, saidmetal band fixedly held within said housing.

[0010] Preferably said metal band is held within the housing in a snapfit arrangement.

[0011] Preferably said projections are integral with said metal band.

[0012] Preferably said projections are burst hole type projections.

[0013] Preferably said burst hole projections include a plurality ofwalls at least some of which are at an angle not substantially parallelto the plane of the metal band.

[0014] Preferably said burst hole projections include a plurality ofwalls at least some of which are at an angle not substantially parallelto the axial angle of the housing.

[0015] Preferably said projections are aligned in at least one annularrow.

[0016] Preferably there are five annular rows extending across saidband.

[0017] Preferably said projections are of different heights.

[0018] Preferably said housing is a split-ring type housing, said metalband correspondingly shaped and sized to be held within said housing.

[0019] In a further form of the invention there is proposed a couplingfor connection of a pipe, said coupling including;

[0020] a hollow body having an external thread extending at least inpart theralong and having a tapered inner surface;

[0021] a nut threadably engaging said body external threads, said nuthaving at one end an internal thread co-operable with said body externalthread and at the other end an outwardly converging inner taperedsurface;

[0022] a deformable gripping member assembly having an outwardlyconverging outer surface and including radially inward projectionscircumferentially disposed in at least one row;

[0023] wherein upon tightening of said nut, said nut inner taperedsurface abuts against and exerts a force on said gripping members outersurface both in the longitudinal and radial directions to thereby causethe gripping member to be urged both radially and longitudinally intosaid body and thereby fixedly retain said pipe.

[0024] Preferably said gripping member assembly: includes a body havinga locking means adapted to engage and hold a metal band, said metal bandincluding the plurality of inwardly directed projections.

BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENT

[0025] The accompanying drawings, which are incorporated in andconstitute a part of this specification, illustrate an implementation ofthe invention and, together with the description, serve to explain theadvantages and principles of the invention. In the drawings,

[0026]FIG. 1 is a central elevational section that shows a pipe endinserted through a sub-assembly comprising a nut, gripping memberassembly, sleeve, and gasket and into a socket in the body of a fittingembodying the present invention;

[0027]FIG. 2 is a similar section showing the configuration of thesub-assembly when the nut is tightened onto the body;

[0028]FIG. 3 is an exploded perspective view of a gripping memberassembly embodying the preset invention including a housing and a metalband;

[0029]FIG. 4 is an exploded side view of the gripping member assembly ofFIG. 1;

[0030]FIG. 5 is a partial perspective view of the metal bandillustrating the projections in detail;

[0031]FIG. 6 is a perspective view of a gripping member assembly,including a grip-ring and a metal band having metal projections,according to a second embodiment of the present invention;

[0032]FIG. 7 is a partial cross-sectional view of a gripping memberassembly of FIG. 6 before tightening of the coupling and where the metalprojections are of a non-uniform size across the metal band; and

[0033]FIG. 8 is a partial cross-sectional view of a gripping memberassembly as in FIG. 7 but when the coupling has been tightened onto apipe.

DESCRIPTION OF TEE PREFERRED EMBODIMENT

[0034] The following detailed description of the invention refers to theaccompanying drawings. Although the description includes exemplaryembodiments, other embodiments are possible, and changes may be made tothe embodiments described without departing from the spirit and scope ofthe invention. Wherever possible, the same reference numbers will beused throughout the drawings and the following description to refer tothe same and like parts.

[0035] It is to be understood that reference to the following transitionfitting is meant by way of example only and the design embodying thepresent invention may equally well be used on other pipe couplingsand/or transition fittings such as Applicant's coupling fittingdescribed in U.S. Pat. No. 5,593,186, Australian provisional patentapplication PR2231 and many other couplings for pipes of the type havinga split or grip ring.

[0036] Shown in FIGS. 1 and 2 is a coupling 10 for outer surfaceengagement of a pipe 12 includes a longitudinal body 14 having malethreads 16 and 18 at each end, the threads adapted for use by nut 20having internal threads 22 that engage the body threads 16 and 18. FIGS.1 and 2 however only illustrate one nut 20 engaging threads 18. It istherefore to be understood that the present invention may equally wellbe used on a pipe coupling having symmetrical ends as well as pipecouplings where one of the ends is adapted for connection to a differenttype of pipe and may accommodate a different fitting.

[0037] The body 14 includes a shoulder defining generally an annularoutwardly diverging surface 24 constituting an abutment surface for aresilient gasket ring 26.

[0038] Surrounding the pipe 12 is a compression sleeve 28 having anoutwardly diverging tapered surface 30 abutting the resilient gasketring. Those skilled in the art will appreciate that any inward relativemotion between the sleeve surface 30 and annular surface 24 will exert aradially inward force on the gasket ring 26 causing it to deform andprovide for a seal between the body 14 and pipe 12 as illustrated inFIG. 2.

[0039] Adjacent but axially outwardly of sleeve 28 is a gripping memberassembly including a housing 32 and a metal band or ring 34 that arereleasably attached to each other, said ring 34 including a plurality ofbarb projections 36.

[0040] The nut 20 includes a tail 38 having an outwardly converginginner tapered surface 40. The housing 32 includes an outwardlyconverging outer tapered surface 42 the included angle of which isapproximately the same as the tapered surface 40 of the nut.

[0041] Upon tightening of the nut 20, its inner surface 40 abuts andslides along the housing outer surface 42 causing both a radial andcompressive force to be experienced by the housing 32. The housingincludes an inner shoulder 44 that abuts against the inner shoulder 46of the sleeve 28 transferring any longitudinal force and thereby actingto compress the gasket ring 26.

[0042] The nut includes an abutment surface 48 that upon tighteningapproaches and may abut the end surface 50 of the body, this dependingon the relative size and aspect ratio of the part making up thecoupling.

[0043] Assuming that the pipe 12 is inserted into the coupling as shownin FIGS. 1 and 2, initial tightening of the nut 20 on the body 14 causesboth a radial and longitudinal force on the housing 32 to bear againstand engage the pipe 12. Continued tightening of the nut when the gasketring has been compressed causes the housing and the metal band to becompressed even further forcing the projections with some force againstthe pipe 12.

[0044] Those skilled in the art will appreciate that the projectionswill bite into the pipe, the amount of bite or penetration depending onthe relative materials. Use of metal projections on a soft plastic pipecauses them to bite into the pipe, whilst use of metal projections on ametal pipe typically causes them to bite to a lesser extent but stillengage the pipe to resist any outward movement of the pipe from thebody.

[0045] The skilled addressee will also appreciate that the configurationof the housing and the metal band enables the present invention to beused for pipes that may vary in diameter. This comparison is illustratedin FIGS. 1 and 2, where even though the pipe in FIG. 2 is smaller thanthat in FIG. 1, the fitting is able to accommodate and suitably seal thesmaller pipe by virtue of the properties of the grip ring assembly andthe seal.

[0046] The housing and the metal band are illustrated in more detail inFIGS. 3 and 4. The housing 32 needs to be both radially deformable andis a split type housing having two ends 52 and 54 that approach eachother as the housing is compressed. The housing 32 includes a flatannular surface 56 defined at one end by a flange 58 and at the otherend opening 60 having an outwardly diverging lip 62. The metal band 34is a split ring correspondingly shaped to and mounted on surface 56. Themetal band 34 includes apertures 64 that engage appropriately positionedprojections 66 on the surface 56. Ends of the metal band 68 and 70engage slots 72 and 74 respectively, the slots located at the ends 52and 54 of the housing 32. It will now be apparent to the skilledaddressee that when the metal band has so been located within thehousing it is locked into place forming a single gripping ring assemblythat moves in uniform and where any forces experienced by the housingare transmitted to the metal band.

[0047] Typically the metal band includes a plurality of inwardlyextending projections 36, this embodiment illustrating five annular rowsof projections, the projections in each row also longitudinally aligned.It is understood that the number and relative orientation of projectionsis not intended to be limited to this particular embodiment.

[0048] The projections are typically manufactured by using a metalpunching process. This method of manufacture has particular advantagesthat shall now be discussed.

[0049] When using a stamping process, a flat band of metal can bepunched simultaneously by a plurality of tools, each tool responsiblefor making one projection. Typically the tool used completely penetratesthrough the metal band causing a break through the band and resulting ina burst hole having sharp protrusions, the number, shape, andorientation depending to some degree on the shape of the tool.

[0050] As illustrated in FIG. 5, use of a square or rectangular shapedtool results in the projections being of the same type. When a foursided tool is used, punching through the metal band results in the metalflowering with there being defined four walls 76 a, 76 b, 76 c, and 76d, the top of each wall ending in a sharp apex 78. Further, the wallsare oriented in the same orientation as was the tool during the punchingprocess.

[0051] It has therefore been discovered, that if the tools used to punchthough the metal band are oriented such that their sides are notparallel to either the longitudinal axis 80 or the parallel axis 82 thewalls defining each of the projections are also not parallel to eitherof those axis. Thus, as shown in FIG. 5, if the tool is a square shapedtool and its sides are at an angle of some 45 degrees to either axis 80or 82, than the walls 76 of the projections are also oriented at anangle of some 45 degrees. These types of projections are advantageousfor several reasons.

[0052] Firstly, the projections' having multiple sharp apexes assists inengaging the pipe. Secondly the orientation of the projections notparallel to either axis 80 or 82 ensures that each projection resistsboth longitudinal and rotational motion of the pipe within the coupling.Those skilled in the art will now appreciate that if the walls of theprojections were longitudinally axially aligned, the coupling would notbe as effective in resisting,longitudinal movement of the pipe whilst ifthe walls of the projections were radially aligned the coupling wouldnot be as effective in resisting relative rotational movement of thepipe with respect to the coupling, that is, the housing.

[0053] It has been found that pressed metal burst holes or teeth providesufficiently sharp or jagged edge to engage a plastic pipe and yet havethe inherent strength to also engage a metal pipe. The punch systemallows one to use a very thin strip of metal that is flexible but allowsone to put onto that metal surface a number of projections that aid inthe gripping of the pipe.

[0054] It will be appreciated by those skilled in the art that the metalband must be sufficiently thin to allow it to follow the contours of thegripping ring housing and yet thick enough to provide the necessarystrength to support the projections.

[0055] The projections may be arranged in annular rows, each row havinga plurality of circumferentially spaced projections. For smallerdiameter pipes it has been found sufficient for only several annularrows of projections. Larger pipes may very well require multiple annularrows.

[0056] Referring now specifically to FIG. 6 here is shown an alternativeembodiment of the present invention including a grip-ring assemblyhaving a grip-ring 84, the grip-ring 84 adapted to snap-fittingly hold ametal band 34 with multiple barb projections 36, the grip-ring 84 alsohaving annular projections 86 adapted to engage a pipe 12. Thisembodiment of the grip-ring assembly thus has a combination of bothmetal projections that are located on the metal band and plasticprojections that are a part of the grip-ring with there being two-rowsof metal projections on the metal band 34.

[0057] It is to be understood that the relative hight andcross-sectional shape of the projections may vary. As illustrated inFIGS. 7 and 8 with reference to the second embodiment of the grip ringassembly as shown in FIG. 6, the height of the projections may vary withdistance into the grip-ring, with the forward most projections 88 beingsmaller than the middle ones 90 that are themselves smaller than theinside ones 92. The projections of FIGS. 7 and 8 are also seen to have aflat apex and in contrast to the first embodiment are not of the burstmetal type but rather of a conical shape type. It is however notintended to limit the size differential to one that decreases uniformly.For example, variable height projections may be randomly scattered alongthe metal band.

[0058] Those skilled in the art will appreciate that the various metalon the metal band may be randomly scattered along the surface of themetal band. The relative sizes of the projections may also be varied.

[0059] Although the invention has been shown and described in what isconceived to be the most practical and preferred embodiment, it isrecognized that departures may be made therefrom within the scope andspirit of the invention, which is not to be limited to the detailsdisclosed herein but is to be accorded the fill scope of the claims soas to embrace any and all equivalent devices and apparatus.

[0060] In any claims that follow and in the summary of the invention,except where the context requires otherwise due to express language ornecessary implication, the word “comprising” is used in the sense of“including”, i.e. the features specified may be associated with furtherfeatures in various embodiments of the invention.

1. A pipe coupling or transition fitting of the type having a deformablegripping member assembly including a housing and a plurality of metalprojections extending inwardly therefrom.
 2. A pipe coupling ortransition fitting as in claim 1 wherein said housing is annular withsaid projections extending circumferentially inwardly from said housing.3. A pipe coupling or transition fitting as in claim 1 wherein saidmetal projections extend from a metal band, said metal band fixedly heldwithin said housing.
 4. A pipe coupling or transition fitting as in anyone of the above claims wherein said metal band is held within thehousing in a snap fit arrangement.
 5. A pipe coupling or transitionfitting as in any one of the above claims wherein said projections areintegral with said metal band.
 6. A pipe coupling or transition fittingas in claim 5 wherein said projections are burst hole type projections.7. A pipe coupling or transition fitting as in claim 6 wherein saidburst hole projections include a plurality of walls at least some ofwhich are at an angle not substantially parallel to the plane of themetal band.
 8. A pipe coupling or transition fitting as in claim 6 orclaim 7 wherein said burst hole projections include a plurality of wallsat least some of which are at an angle not substantially parallel to theaxial angle of the housing.
 9. A pipe coupling or transition fitting asin any one of the above claims wherein said projections are aligned inat least one annular row.
 10. A pipe coupling or transition fitting asin claim 9 wherein there are five annular rows extending across saidband.
 11. A pipe coupling or transition fitting as in any one of theabove claims wherein said projections are of different heights.
 12. Apipe coupling or transition fitting as in any one of the above claimswherein said housing is a split-ring type housing, said metal bandcorrespondingly shaped and sized to be held within said housing.
 13. Acoupling for connection of a pipe, said coupling including; a hollowbody having an external thread extending at least in part theralong andhaving a tapered inner surface; a nut threadably engaging said bodyexternal threads, said nut having at one end an internal threadco-operable with said body external thread and at the other end anoutwardly converging inner tapered surface; a deformable gripping memberassembly having an outwardly converging outer surface and includingradially inward projections circumferentially disposed in at least onerow; wherein upon tightening of said nut, said nut inner tapered surfaceabuts against and exerts a force on said gripping members outer surfaceboth in the longitudinal and radial directions to thereby cause thegripping member to be urged both radially and longitudinally into saidbody and thereby fixedly retain said pipe.
 14. A coupling as in claim 13wherein said gripping member assembly includes a body having a lockingmeans adapted to engage and hold a metal band, said metal band includingthe plurality of inwardly directed projections.